UN relief officials warned Monday that tens of thousands of people affected by the earthquake and tsunami in South Asia had not received help and that some were at risk of dying because ruined roads and bad communications were preventing the distribution of supplies.

International relief groups have delivered only one-eighth of the 400,000 tons of food flown and trucked into the Indonesia city of Banda Aceh by the UN World Food Program, said Michael Elmquist, chief of the UN office coordinating the rescue effort in the country. He said the delivery of lifesaving food and medicine has been slowed by impassable highways, severed telecommunications and airports unable to accommodate enough relief flights.

"I have witnessed a buildup of aid on a scale that has never happened before," Elmquist said. "This effort has been hampered very seriously."

Early Tuesday, a Boeing 737 was stranded on the runway at the Banda Aceh airport for more than 10 hours, delaying other relief shipments, after the plane reportedly hit a buffalo when it tried to land. Workers were able to tow the plane off the runway late in the day.

At the United Nations, Jan Egeland, the UN emergency relief coordinator, said Monday that it was impossible to estimate how many people had not received emergency aid since the Dec. 26 earthquake that generated the tsunami off the northern coast of Indonesia's Sumatra island.

"My heart goes out to those along the Sumatra coast, because we're not even there, and those were the hardest hit," Egeland said. "Are they tens of thousands, are they hundreds of thousands that we're not reaching? I don't even know."

Egeland estimated that fatalities from the catastrophe now exceeded 150,000. The official death count is about 139,000, including more than 94,000 in Indonesia and 30,000 in Sri Lanka, the island nation off the southern tip of India. The tsunami killed people in coastal areas in nine other countries around the Indian Ocean. Throughout the region, about 500,000 people may have been seriously injured and millions left homeless, UN officials said.

"The death toll will grow exponentially on the western coast of Sumatra," Egeland said at a news conference.

The World Food Program reported Monday that 30,000 people in Burma needed emergency help, despite milder assessments from the country's secretive military government. International aid agencies have estimated that as many as 90 people were killed in Burma, but some experts said the toll could be significantly higher. A computer model by Steven N. Ward, a geophysicist at the University of California at Santa Cruz, indicated that the wave hit Burma as hard as adjacent areas of southern Thailand, where at least 5,000 people are reported to have been killed.

US military helicopters on Monday ferried dozens of victims from isolated zones in Aceh province, located in northern Sumatra, to the provincial capital, Banda Aceh, the Associated Press reported. Those rescued included children, elderly people and two pregnant women. Doctors said victims suffered from pneumonia, broken bones, infected wounds and tetanus, and many were in critical condition or traumatized.

"In my 17 years of service, I have never seen such devastation, and I hope that I'll never see such again in my life," Senior Chief Petty Officer Jesse Cash, who helped ferry the victims to safety, told the Associated Press.

Over the weekend, the US Navy began deploying helicopters from the USS Abraham Lincoln, an aircraft carrier stationed off Sumatra.

"There's a major, impressive humanitarian operation, but it's encumbered by the enormous difficulties of logistics," said Peter Holdsworth, who coordinates rapid-response missions for ECHO, the European Commission's emergency aid delivery arm. "Through no fault of the people on the ground, we're still a little bit behind the curve."

Officials said they had adequate resources for the effort, with $2 billion in contributions from foreign governments, aid institutions and individuals. "The real problem is going to be the ability to actually use that cash," Holdsworth said.

Elsewhere, an Indian coast guard ship found four Indonesian fishermen who had been drifting in their wooden dinghy for more than a week, after the earthquake and tsunami destroyed their homes.

In Somalia, a spokesman for President Abdullahi Yusuf said promised relief from 24 countries -- including the United States, Italy, Germany and Saudi Arabia -- had not arrived. Officials said at least 50,000 people urgently needed food, water, shelter and medical help after massive waves destroyed houses and ruined livelihoods. The East African country is more than 3,000 miles from the epicenter of the 9.0-magnitude earthquake.

In Banda Aceh, relief flights from Sumatra's largest city, Medan, were delayed up to five hours because there were not enough landing areas for aircraft or forklifts to unload supplies. Early Tuesday morning, the airport in Banda Aceh was shut down after an Indonesian Boeing 737 hit what US and Indonesian officials described as a buffalo as the aircraft landed. One of the plane's left wheels collapsed, leaving it stranded on the runway until workers pulled it out of the way.

Capt. Andy Rice, a US Marine attache, said the incident did not interfere with relief operations because helicopters and trucks had large amounts of goods on the ground that still needed to be distributed around the region. Still, aircraft were unable to land for more than 10 hours.

Relief was flowing to dozens of refugee camps in and around Banda Aceh. An Australian government medical team has taken over and restored an abandoned hospital, and Australian soldiers on Monday began dispensing cans of treated water on city streets. International aid workers could be seen throughout the city dispensing generators, food and water treatment kits to people who have lost nearly everything they had.

But beyond the city, the flow of help has been scarce and uneven. The road connecting Banda Aceh to points south was blocked about seven miles outside the city: The bridge crossing a muddy river there lies twisted in the water. A former military base next to it was annihilated, and rubble and rotting corpses were strewn across a flooded field.

Where the road gave way to the river, Indonesian volunteers filled a boat with sacks of rice, boxes of noodles and bottles of drinking water to deliver to survivors in towns and villages on the other side. People who visited communities there in recent days said survivors were living on whatever they could find and were almost entirely without aid.

Abdullah Samsuardi, a survivor from Aceh Jaya, about 60 miles down the west coast of Aceh, said only 80 of the town's 3,000 inhabitants remained there. The rest either were dead or in refugee camps.

Samsuardi had been in Aceh Jaya until Sunday evening, when he saw a Singaporean army helicopter flying overhead. He waved his arms frantically, and the crew landed to pick him up along with four other survivors.

Those left behind are staying mainly to take care of injured relatives, Samsuardi said. They are subsisting on coconuts and food from others passing by on the way to refugee camps, he said. They are drinking well water, and many people are suffering from diarrhea. "Until the first boat came yesterday, no one came with anything," he said.

Some relief officials said they did not have enough helicopters and airplanes to transport people and equipment into the field quickly. Dozens of aid workers and their gear have been stranded in Banda Aceh and Medan.

For several days, Spanish, French and German Red Cross units have been seeking helicopters large enough to ferry mobile water treatment plants to towns on the west coast, said Langdon Greenhalgh, an American who handles relief logistics for the International Federation of Red Cross and Red Crescent Societies.

Mabrook Brahmi, logistics coordinator for Action Contra la Faim, a French-Spanish group that specializes in clean water and emergency food aid, said Monday night that he had been trying for two days to find a flight to the coast so he could assess relief needs.

Peter S. Goodman
Staff writer Colum Lynch at the United Nations and correspondent Alan Sipress in Banda Aceh contributed to this report.